cabalPlan2nix

WORK IN PROGRESS

Generate Nix derivations from Cabal plan.json files.

cabalPlan2nix is a Nix tool that converts Cabal's plan.json files into Nixpkgs-compatible Haskell package sets.

Quick Start

Flake Input

Add to your flake.nix:

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    cabalPlan2nix.url = "github:solomon-b/cabalPlan2nix";
  };

  outputs = { self, nixpkgs, cabalPlan2nix }:
    let
      system = "x86_64-linux";
      pkgs = nixpkgs.legacyPackages.${system};

      # Generate the Haskell package set from the example's plan.json
      examplePlan = pkgsWithOverlay.haskell.lib.cabalPlan2nix ./path/to/plan.json "base/path/prefix/from/plan/file";

      # Generate package set from your plan.json
      haskellPackages = pkgs.haskell.packages.ghc98.extend examplePlan.overlay;

    in {
      # Use myPackages overlay with your Haskell package set
      packages.${system}.default = haskellPackages.myPackage;
    };
}

Direct Import

let
  pkgs = import <nixpkgs> { overlays = [ (import /path/to/cabalPlan2nix/nix/overlay.nix) ]; };
  examplePlan = pkgs.haskell.lib.cabalPlan2nix ./plan.json;
  haskellPackages = pkgs.haskell.packages.ghc98.extend examplePlan.overlay;
in
  haskellPackages.myPackage

Generating plan.json

Generate a plan.json file using Cabal:

cabal build --dry-run ; cp dist-newstyle/cache/plan.json .

This creates a plan.json file in dist-newstyle/cache/ that contains the complete build plan computed by Cabal's dependency solver.

License